A picture is worth a thousand words – or, more precisely, $288m. That was the sum tech entrepreneur Elon Musk donated to Donald Trump’s presidential election campaign. His reward was dramatically illustrated by the cover of this week’s Time magazine: an image of Musk, coffee cup in hand, sitting behind the Resolute desk used by every US president since Jimmy Carter. Some speculated that the picture of “President Musk” was designed to provoke the thin-skinned Trump, who is known to revere Time magazine and has twice been named its “person of the year”. The president reacted on Friday with a...